Flexible Ionic Diodes with High Rectifying Ratio and Wide Temperature Tolerance

Abstract

Soft iontronics expand the toolbox of bio‐integrated or bio‐interfaced devices, owing to their natural resemblance with living systems; however, the development for analogous integrated ionic circuits is immature due to the difficulty of fabricating fundamental ionic logic elements. Among these, ionic diodes have motivated great endeavors for their unique ionic current rectifying characteristics. Nonetheless, it is still challenging to achieve high‐performance ionic diodes; also, most reported aqueous solution‐based ionic diodes fail to work at extreme temperatures, seriously hindering their practical uses. This work reports a highly rectifying, temperature‐tolerant, and flexible hydrogel ionic diode enabled by an ethylene glycol/water binary solvent system. The ionic diodes exhibit outstanding dehydration resistance to high temperatures (100 °C) and anti‐freezing performance at low temperatures (−20 °C). Rectification ratios as high as 1201 (with 0% ethylene glycol content) and 566 (with 40% EG content) are achieved, which are distinctly advantageous over most previous reports. A flexible four‐diode bridge full‐wave rectifier circuit is then fabricated, and its integration with the triboelectric nanogenerator for effective biomechanical energy harvesting is demonstrated. This work is believed to open up new insights for the development of future bio‐interfaced applications.

Environment‐tolerant ionic hydrogel–elastomer hybrids with robust interfaces, high transparence, and biocompatibility for a mechanical–thermal multimode sensor

“…With the rapid development of big data and the Internet of Things, more advanced and intelligent wearable electronic devices must be urgently developed to meet new requirements 1–3 . Flexible and stretchable sensors are essential components in wearable electronic devices, and they have attracted increasing interest for their versatile applications, such as in soft robots, healthcare, and human–machine interfacing facilities, owing to their repeatable electrical changes and high sensing sensitivity 4–8 . Conductive hydrogels with high conductivity, flexibility, and adjustable mechanical properties and comprising hydrophilic three‐dimensional polymer networks swollen with a large amount of water are ideal candidates for soft conductors for assembling wearable sensors 9,10 .…”

A Pseudocapacitor Diode Based on Ion‐Selective Surface Redox Effect

“…The feasible temperature range of diodes is actually important for their practical application. [ 21 ] For the pseudocapacitor diode, the EIS test shows that the slope of the low‐frequency range increases as the temperature rises (Figure 3g), which also means that the ionic conduction of the device is accelerated. As displayed in Figure 3h, as the temperature rises, the capacity and RR II hardly decay, even at 60 °C (the capacity remains at 100.1% of that at 20 °C and the RR II remains at 0.85).…”

Structural Flexibility in Triboelectric Nanogenerators: A Review on the Adaptive Design for Self-Powered Systems

“…Guo et al reported an integrated temperature-resistant and flexible hydrogel ion diode with a triboelectric nanogenerator [ 60 ]. The diode is highly rectified by a binary ethylene glycol/water solvent system and can work from −20 °C to 100 °C.…”